The implantologic rehabilitation of patients after ablative oral tumour surgery and defect reconstruction is carried out generally without strict assessment of the successfulness of the outcome. Therefore 210 dental implants inserted in 58 tumour patients were subjected to regular follow-up examinations for 5 years. The Bone-Lock osseointegrated implant system (Howmedica Leibinger, Freiburg) was used exclusively. The plaque index (Silness and Löe), the sulcus bleeding index (Löe), the pocket probing depth, the width of the passive peri-implant tissue, implant mobility by means of the Periotest method and bone resorption according to X-ray findings were ascertained. At 60-70% of measurement points a passive peri-implant tissue was created. After the beginning of loading, specific adaptation phenomena of tumour patients could be detected. Despite constant plaque accumulation (mean 1.79), the bleeding disposition diminished from maximal 1.83 to 0.71. Corresponding to this finding the pocket probing depths decreased from 5.75 mm to 4.57 mm. The implant mobility (Periotest method: mean 2.25, range -3 to +8.5) showed a decrease in the first 2 years, then the values increased. The mobility depends on the kind of supraconstruction. Ball attachments have the lowest and implant-supported bridges have the highest values. Peri-implant bone resorption showed 1.43 mm as a mean value of all measurements and had a horizontal component of 73-84%. In accordance with this the vertical bone loss was small. After an increase during the first 2 years both values reached a steady state around 2.5 mm. The success rate for all 210 inserted implants is 83.2%. For implants in place for over 365 days the success rate is 93%. Prosthetic restoration in tumour patients can be achieved with osseointegrated dental implants according to the acknowledged international standards.